Lingual (pharyngeal) lipase is secreted by serous glands of the pharynx and acts in the stomach at pH 5.4 to hydrolyze dietary triacylglycerol to mostly diacylglycerol and fatty acids. These amphipathic products facilitate emulsification of lipid in the stomach and upper smaller intestines. We have recently purified lingual lipase from serous glands of rat tongue with a specific activity of 230 units/mg protein. The molecular weight of the active form of the enzyme is 51,000. Studies with purified lipase show that bile salts (sodium taurodeoxycholate) and calcium ions together enhance greatly the action of lingual lipase on long chain triacyglycerol and expand the pH optimum to 6.5. Diacylglycerol and monoacylglycerol are also hydrolyzed but at slower rates. These findings indicate that lingual lipase can act on dietary fat in the small intestines and thereby could be beneficial in cases of pancreatic insufficiency.